fix(pu): align Sampled EfficientZero obs shape

[puyuan1996]

Closes #484

Summary

• Replace env.obs_shape with env.observation_shape in atari_sampled_efficientzero_config.py.
• Explicitly align Sampled EfficientZero Atari env/model shape-related fields for 64x64 grayscale stack-4 observations.
• Add legacy *NoFrameskip-v4 aliases to the Atari action-space map so existing configs such as PongNoFrameskip-v4 still import correctly.
• Add config-level regression tests for the observation-shape alignment and legacy action-space map ids.

Tests

• /mnt/shared-storage-user/puyuan/lz/bin/python -m pytest zoo/atari/tests/test_atari_sampled_efficientzero_config.py -q
• /mnt/shared-storage-user/puyuan/lz/bin/python -m py_compile zoo/atari/config/atari_env_action_space_map.py zoo/atari/config/atari_sampled_efficientzero_config.py zoo/atari/tests/test_atari_sampled_efficientzero_config.py
• MPLCONFIGDIR=/tmp/matplotlib /mnt/shared-storage-user/puyuan/lz/bin/python smoke test that runs zoo/atari/config/atari_sampled_efficientzero_config.py as __main__ with train_muzero stubbed.